Rancid Rabbit (voiced by Billy West) is the stereotypical authority figure and is a semi-antagonist of the series. He had his job titles like police officer, life guard, prison guard, firefighter, boss of various businesses, principal, president, mayor, Egyptian pharaoh, doctor, TV host, contest judge, store and Taco Depot manager. In one episode, he appears as a principal at a school and at the end, as a police officer. He also was seen as a dentist in "Teeth for Two." He also was a lifeguard in "Escape from the Deep End". He also had a restraint named Rancid Rib Room in "Sumo Enchanted Evening".

Rancid takes advantage of CatDog as much as he can by deceiving them into buying his products or pushing them to do his bidding in a job. He does whatever it takes to take their money or benefit himself in any way, even if it means abusing his power to the fullest degree. However, he is shown to help CatDog when he works as a doctor whenever something goes wrong between the two, so he can sometimes be seen as more of an anti-hero than a villain. He constantly says "Leaping lumbago." and "What, what, what?" Rancid owns a mall called the Mall of Malls (a parody of the Mall Of America), and has a spoiled niece named Rancine. Rancid also has a cousin named Rotten, who lives in Farburg.